Methods For Metal Oxide Post-Treatment

ABSTRACT

Methods comprising forming a metal oxide film by atomic layer deposition using water as an oxidant are described. The metal oxide film is exposed to a decoupled plasma comprising one or more of He, H2 or O2 to lower the wetch etch rate of the metal oxide film.

TECHNICAL FIELD

The present disclosure relates generally to methods of depositing thinfilms. In particular, the disclosure relates to processes for theselective deposition of aluminum oxide films with post-deposition plasmatreatment.

BACKGROUND

Thin films are widely used in semiconductor fabrication for manyprocesses. For example, thin films (e.g., aluminum oxide) are used inmulti-patterning processes as spacer materials to achieve smaller devicedimensions without employing the most expensive EUV lithographytechnology.

Traditional fabrication processes include conformal film deposition on3D structures (e.g., fins) followed by wet or dry etching to removeportions of the layer. The removability or the etch resistance of thefilm can affect the process uniformity, repeatability and accuracy.Changing the wet or dry etch rate of the film without affecting filmthickness could provide greater control over patterning applications.

Therefore, there is a need in the art for processes of controlling thewet or dry etch rates of films.

SUMMARY

One or more embodiments of the disclosure are directed to methodscomprising forming a metal oxide film on a substrate surface by ALDusing water as an oxidant. The metal oxide film is exposed to adecoupled plasma comprising one or more of He, H₂ or O₂, to lower thewet etch rate of the metal oxide film.

Additional embodiments of the disclosure are directed to methodscomprising forming an aluminum oxide film on a substrate surface bysequential exposure to an aluminum precursor and water. The aluminumoxide film is exposed to a decoupled plasma comprising a mixture ofoxygen and helium. The decoupled plasma has a source power and no bias.

Further embodiments of the disclosure are directed to methods comprisingforming an aluminum oxide film on a substrate surface by sequentialexposure to an aluminum precursor and water. The aluminum oxide film isexposed to a decoupled plasma consisting essentially of helium. Thedecoupled plasma has a source power and a bias power.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows a schematic view of a processing platform in accordancewith one or more embodiment of the disclosure;

FIG. 2 shows a cross-sectional view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 3 shows a partial perspective view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 5 shows a schematic view of a portion of a wedge shaped gasdistribution assembly for use in a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 6 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure; and

FIG. 7 shows a schematic representation of a method in accordance withone or more embodiment of the disclosure.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present disclosure, any of the film processingsteps disclosed may also be performed on an under-layer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such under-layer as the contextindicates. Thus for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

FIG. 1 shows a processing platform 100 in accordance with one or moreembodiment of the disclosure. The embodiment shown in FIG. 1 is merelyrepresentative of one possible configuration and should not be taken aslimiting the scope of the disclosure. For example, in some embodiments,the processing platform 100 has different numbers of process chambers,buffer chambers and robot configurations.

The processing platform 100 includes a central transfer station 110which has a plurality of sides 111, 112, 113, 114, 115, 116. Thetransfer station 110 shown has a first side 111, a second side 112, athird side 113, a fourth side 114, a fifth side 115 and a sixth side116. Although six sides are shown, those skilled in the art willunderstand that there can be any suitable number of sides to thetransfer station 110 depending on, for example, the overallconfiguration of the processing platform 100.

The transfer station 110 has a robot 117 positioned therein. The robot117 can be any suitable robot capable of moving a wafer duringprocessing. In some embodiments, the robot 117 has a first arm 118 and asecond arm 119. The first arm 118 and second arm 119 can be movedindependently of the other arm. The first arm 118 and second arm 119 canmove in the x-y plane and/or along the z-axis. In some embodiments, therobot 117 includes a third arm or a fourth arm (not shown). Each of thearms can move independently of other arms.

A batch processing chamber 120 can be connected to a first side 111 ofthe central transfer station 110. The batch processing chamber 120 canbe configured to process x wafers at a time for a batch time. In someembodiments, the batch processing chamber 120 can be configured toprocess in the range of about four (x=4) to about 12 (x=12) wafers atthe same time. In some embodiments, the batch processing chamber 120 isconfigured to process six (x=6) wafers at the same time. As will beunderstood by the skilled artisan, while the batch processing chamber120 can process multiple wafers between loading/unloading of anindividual wafer, each wafer may be subjected to different processconditions at any given time. For example, a spatial atomic layerdeposition chamber, like that shown in FIGS. 2 through 6, expose thewafers to different process conditions in different processing regionsso that as a wafer is moved through each of the regions, the process iscompleted.

FIG. 2 shows a cross-section of a processing chamber 200 including a gasdistribution assembly 220, also referred to as injectors or an injectorassembly, and a susceptor assembly 240. The gas distribution assembly220 is any type of gas delivery device used in a processing chamber. Thegas distribution assembly 220 includes a front surface 221 which facesthe susceptor assembly 240. The front surface 221 can have any number orvariety of openings to deliver a flow of gases toward the susceptorassembly 240. The gas distribution assembly 220 also includes an outeredge 224 which in the embodiments shown, is substantially round.

The specific type of gas distribution assembly 220 used can varydepending on the particular process being used. Embodiments of thedisclosure can be used with any type of processing system where the gapbetween the susceptor and the gas distribution assembly is controlled.While various types of gas distribution assemblies can be employed(e.g., showerheads), embodiments of the disclosure may be particularlyuseful with spatial gas distribution assemblies which have a pluralityof substantially parallel gas channels. As used in this specificationand the appended claims, the term “substantially parallel” means thatthe elongate axis of the gas channels extend in the same generaldirection. There can be slight imperfections in the parallelism of thegas channels. In a binary reaction, the plurality of substantiallyparallel gas channels can include at least one first reactive gas Achannel, at least one second reactive gas B channel, at least one purgegas P channel and/or at least one vacuum V channel. The gases flowingfrom the first reactive gas A channel(s), the second reactive gas Bchannel(s) and the purge gas P channel(s) are directed toward the topsurface of the wafer. Some of the gas flow moves horizontally across thesurface of the wafer and out of the process region through the purge gasP channel(s). A substrate moving from one end of the gas distributionassembly to the other end will be exposed to each of the process gasesin turn, forming a layer on the substrate surface.

In some embodiments, the gas distribution assembly 220 is a rigidstationary body made of a single injector unit. In one or moreembodiments, the gas distribution assembly 220 is made up of a pluralityof individual sectors (e.g., injector units 222), as shown in FIG. 3.Either a single piece body or a multi-sector body can be used with thevarious embodiments of the disclosure described.

A susceptor assembly 240 is positioned beneath the gas distributionassembly 220. The susceptor assembly 240 includes a top surface 241 andat least one recess 242 in the top surface 241. The susceptor assembly240 also has a bottom surface 243 and an edge 244. The recess 242 can beany suitable shape and size depending on the shape and size of thesubstrates 60 being processed. In the embodiment shown in FIG. 2, therecess 242 has a flat bottom to support the bottom of the wafer;however, the bottom of the recess can vary. In some embodiments, therecess has step regions around the outer peripheral edge of the recesswhich are sized to support the outer peripheral edge of the wafer. Theamount of the outer peripheral edge of the wafer that is supported bythe steps can vary depending on, for example, the thickness of the waferand the presence of features already present on the back side of thewafer.

In some embodiments, as shown in FIG. 2, the recess 242 in the topsurface 241 of the susceptor assembly 240 is sized so that a substrate60 supported in the recess 242 has a top surface 61 substantiallycoplanar with the top surface 241 of the susceptor 240. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within 0.5 mm, ±0.4 mm, ±0.35 mm, ±0.30 mm,±0.25 mm, ±0.20 mm, ±0.15 mm, ±0.10 mm or ±0.05 mm.

The susceptor assembly 240 of FIG. 2 includes a support post 260 whichis capable of lifting, lowering and rotating the susceptor assembly 240.The susceptor assembly may include a heater, or gas lines, or electricalcomponents within the center of the support post 260. The support post260 may be the primary means of increasing or decreasing the gap betweenthe susceptor assembly 240 and the gas distribution assembly 220, movingthe susceptor assembly 240 into proper position. The susceptor assembly240 may also include fine tuning actuators 262 which can makemicro-adjustments to susceptor assembly 240 to create a predeterminedgap 270 between the susceptor assembly 240 and the gas distributionassembly 220.

In some embodiments, the gap 270 distance is in the range of about 0.1mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, orin the range of about 0.1 mm to about 2.0 mm, or in the range of about0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm,or in the range of about 0.4 mm to about 1.6 mm, or in the range ofabout 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the rangeof about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm toabout 1.1 mm, or about 1 mm.

The processing chamber 200 shown in the Figures is a carousel-typechamber in which the susceptor assembly 240 can hold a plurality ofsubstrates 60. As shown in FIG. 3, the gas distribution assembly 220 mayinclude a plurality of separate injector units 222, each injector unit222 being capable of depositing a film on the wafer, as the wafer ismoved beneath the injector unit. Two pie-shaped injector units 222 areshown positioned on approximately opposite sides of and above thesusceptor assembly 240. This number of injector units 222 is shown forillustrative purposes only. It will be understood that more or lessinjector units 222 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 222 to form a shapeconforming to the shape of the susceptor assembly 240. In someembodiments, each of the individual pie-shaped injector units 222 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 222. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 240and gas distribution assembly 220 to load/unload substrates 60.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 4, the processing chamber200 has four gas injector assemblies and four substrates 60. At theoutset of processing, the substrates 60 can be positioned between thegas distribution assemblies 220. Rotating 17 the susceptor assembly 240by 45° will result in each substrate 60 which is between gasdistribution assemblies 220 to be moved to a gas distribution assembly220 for film deposition, as illustrated by the dotted circle under thegas distribution assemblies 220. An additional 45° rotation would movethe substrates 60 away from the gas distribution assemblies 220. Thenumber of substrates 60 and gas distribution assemblies 220 can be thesame or different. In some embodiments, there are the same numbers ofwafers being processed as there are gas distribution assemblies. In oneor more embodiments, the number of wafers being processed are fractionof or an integer multiple of the number of gas distribution assemblies.For example, if there are four gas distribution assemblies, there are 4×wafers being processed, where x is an integer value greater than orequal to one. In an exemplary embodiment, the gas distribution assembly220 includes eight process regions separated by gas curtains and thesusceptor assembly 240 can hold six wafers.

The processing chamber 200 shown in FIG. 4 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 200 includes a pluralityof gas distribution assemblies 220. In the embodiment shown, there arefour gas distribution assemblies 220 (also called injector assemblies)evenly spaced about the processing chamber 200. The processing chamber200 shown is octagonal; however, those skilled in the art willunderstand that this is one possible shape and should not be taken aslimiting the scope of the disclosure. The gas distribution assemblies220 shown are trapezoidal, but can be a single circular component ormade up of a plurality of pie-shaped segments, like that shown in FIG.3.

The embodiment shown in FIG. 4 includes a load lock chamber 280, or anauxiliary chamber like a buffer station. This chamber 280 is connectedto a side of the processing chamber 200 to allow, for example thesubstrates (also referred to as substrates 60) to be loaded/unloadedfrom the chamber 200. A wafer robot may be positioned in the chamber 280to move the substrate onto the susceptor.

Rotation of the carousel (e.g., the susceptor assembly 240) can becontinuous or intermittent (discontinuous). In continuous processing,the wafers are constantly rotating so that they are exposed to each ofthe injectors in turn. In discontinuous processing, the wafers can bemoved to the injector region and stopped, and then to the region 84between the injectors and stopped. For example, the carousel can rotateso that the wafers move from an inter-injector region across theinjector (or stop adjacent the injector) and on to the nextinter-injector region where the carousel can pause again. Pausingbetween the injectors may provide time for additional processing stepsbetween each layer deposition (e.g., exposure to plasma).

FIG. 5 shows a sector or portion of a gas distribution assembly 220,which may be referred to as an injector unit 222. The injector units 222can be used individually or in combination with other injector units.For example, as shown in FIG. 6, four of the injector units 222 of FIG.5 are combined to form a single gas distribution assembly 220. (Thelines separating the four injector units are not shown for clarity.)While the injector unit 222 of FIG. 5 has both a first reactive gas port225 and a second gas port 235 in addition to purge gas ports 255 andvacuum ports 245, an injector unit 222 does not need all of thesecomponents.

Referring to both FIGS. 5 and 6, a gas distribution assembly 220 inaccordance with one or more embodiment may comprise a plurality ofsectors (or injector units 222) with each sector being identical ordifferent. The gas distribution assembly 220 is positioned within theprocessing chamber and comprises a plurality of elongate gas ports 225,235, 245 in a front surface 221 of the gas distribution assembly 220.The plurality of elongate gas ports 225, 235, 245, 255 extend from anarea adjacent the inner peripheral edge 223 toward an area adjacent theouter peripheral edge 224 of the gas distribution assembly 220. Theplurality of gas ports shown include a first reactive gas port 225, asecond gas port 235, a vacuum port 245 which surrounds each of the firstreactive gas ports and the second reactive gas ports and a purge gasport 255.

With reference to the embodiments shown in FIG. 5 or 6, when statingthat the ports extend from at least about an inner peripheral region toat least about an outer peripheral region, however, the ports can extendmore than just radially from inner to outer regions. The ports canextend tangentially as vacuum port 245 surrounds reactive gas port 225and reactive gas port 235. In the embodiment shown in FIGS. 5 and 6, thewedge shaped reactive gas ports 225, 235 are surrounded on all edges,including adjacent the inner peripheral region and outer peripheralregion, by a vacuum port 245.

Referring to FIG. 5, as a substrate moves along path 227, each portionof the substrate surface is exposed to the various reactive gases. Tofollow the path 227, the substrate will be exposed to, or “see”, a purgegas port 255, a vacuum port 245, a first reactive gas port 225, a vacuumport 245, a purge gas port 255, a vacuum port 245, a second gas port 235and a vacuum port 245. Thus, at the end of the path 227 shown in FIG. 5,the substrate has been exposed to the first reactive gas 225 and thesecond reactive gas 235 to form a layer. The injector unit 222 shownmakes a quarter circle but could be larger or smaller. The gasdistribution assembly 220 shown in FIG. 6 can be considered acombination of four of the injector units 222 of FIG. 4 connected inseries.

The injector unit 222 of FIG. 5 shows a gas curtain 250 that separatesthe reactive gases. The term “gas curtain” is used to describe anycombination of gas flows or vacuum that separate reactive gases frommixing. The gas curtain 250 shown in FIG. 5 comprises the portion of thevacuum port 245 next to the first reactive gas port 225, the purge gasport 255 in the middle and a portion of the vacuum port 245 next to thesecond gas port 235. This combination of gas flow and vacuum can be usedto prevent or minimize gas phase reactions of the first reactive gas andthe second reactive gas.

Referring to FIG. 6, the combination of gas flows and vacuum from thegas distribution assembly 220 form a separation into a plurality ofprocess regions 350. The process regions are roughly defined around theindividual gas ports 225, 235 with the gas curtain 250 between 350. Theembodiment shown in FIG. 6 makes up eight separate process regions 350with eight separate gas curtains 250 between. A processing chamber canhave at least two process regions. In some embodiments, there are atleast three, four, five, six, seven, eight, nine, 10, 11 or 12 processregions.

During processing a substrate may be exposed to more than one processregion 350 at any given time. However, the portions that are exposed tothe different process regions will have a gas curtain separating thetwo. For example, if the leading edge of a substrate enters a processregion including the second gas port 235, a middle portion of thesubstrate will be under a gas curtain 250 and the trailing edge of thesubstrate will be in a process region including the first reactive gasport 225.

A factory interface 280, which can be, for example, a load lock chamber,is shown connected to the processing chamber 200. A substrate 60 isshown superimposed over the gas distribution assembly 220 to provide aframe of reference. The substrate 60 may often sit on a susceptorassembly to be held near the front surface 221 of the gas distributionplate 220. The substrate 60 is loaded via the factory interface 280 intothe processing chamber 200 onto a substrate support or susceptorassembly (see FIG. 4). The substrate 60 can be shown positioned within aprocess region because the substrate is located adjacent the firstreactive gas port 225 and between two gas curtains 250 a, 250 b.Rotating the substrate 60 along path 227 will move the substratecounter-clockwise around the processing chamber 200. Thus, the substrate60 will be exposed to the first process region 350 a through the eighthprocess region 350 h, including all process regions between.

Some embodiments of the disclosure are directed to processing methodscomprising a processing chamber 200 with a plurality of process regions350 a-350 h with each process region separated from an adjacent regionby a gas curtain 250. For example, the processing chamber shown in FIG.6. The number of gas curtains and process regions within the processingchamber can be any suitable number depending on the arrangement of gasflows. The embodiment shown in FIG. 6 has eight gas curtains 250 andeight process regions 350 a-350 h.

Referring back to FIG. 1, the processing platform 100 includes apre-clean chamber 140 connected to a second side 112 of the centraltransfer station 110. The pre-clean chamber 140 is configured to exposethe wafers to one or more of a wet etch comprising dilute (1%)hydrofluoric acid or a dry etch comprising a plasma-based etch. Forexample, a plasma-based etch process might expose the substrate surfacea mixture of ammonia and HF.

In some embodiments, the processing platform further comprises a secondbatch processing chamber 130 connected to a third side 113 of thecentral transfer station 110. The second batch processing chamber 130can be configured similarly to the batch processing chamber 120, or canbe configured to perform a different process or to process differentnumbers of substrates.

The second batch processing chamber 130 can be the same as the firstbatch processing chamber 120 or different. In some embodiments, thefirst batch processing chamber 120 and the second batch processingchamber 130 are configured to perform the same process with the samenumber of wafers in the same batch time so that x and y (the number ofwafers in the second batch processing chamber 130) are the same and thefirst batch time and second batch time (of the second batch processingchamber 130) are the same. In some embodiments, the first batchprocessing chamber 120 and the second batch processing chamber 130 areconfigured to have one or more of different numbers of wafers (x notequal to y), different batch times, or both.

In the embodiment shown in FIG. 1, the processing platform 100 includesa second pre-clean chamber 150 connected to a fourth side 114 of thecentral transfer station 110. The second pre-clean chamber 150 can bethe same as the pre-clean chamber 140 or different. In some embodiments,the first and second batch processing chambers 120, 130 are configuredto process the same number of wafers in the same batch time (x=y) andthe first and second single wafer processing chambers 140, 150 areconfigured to perform the same process in the same amount of time(1/x=1/y).

The processing platform 100 can include a controller 195 connected tothe robot 117 (the connection is not shown). The controller 195 can beconfigured to move wafers between the pre-clean chamber 140 and thefirst batch processing chamber 120 with a first arm 118 of the robot117. In some embodiments, the controller 195 is also configured to movewafers between the second single wafer processing chamber 150 and thesecond batch processing chamber 130 with a second arm 119 of the robot117.

The processing platform 100 can also include a first buffer station 151connected to a fifth side 115 of the central transfer station 110 and/ora second buffer station 152 connected to a sixth side 116 of the centraltransfer station 110. The first buffer station 151 and second bufferstation 152 can perform the same or different functions. For example,the buffer stations may hold a cassette of wafers which are processedand returned to the original cassette, or the first buffer station 151may hold unprocessed wafers which are moved to the second buffer station152 after processing. In some embodiments, one or more of the bufferstations are configured to pre-treat, pre-heat or clean the wafersbefore and/or after processing.

In some embodiments, the controller 195 is configured to move wafersbetween the first buffer station 151 and one or more of the pre-cleanchamber 140 and the first batch processing chamber 120 using the firstarm 118 of the robot 117. In some embodiments, the controller 195 isconfigured to move wafers between the second buffer station 152 and oneor more of the second single wafer processing chamber 150 or the secondbatch processing chamber 130 using the second arm 119 of the robot 117.

The processing platform 100 may also include one or more slit valves 160between the central transfer station 110 and any of the processingchambers. In the embodiment shown, there is a slit valve 160 betweeneach of the processing chambers 120, 130, 140, 150 and the centraltransfer station 110. The slit valves 160 can open and close to isolatethe environment within the processing chamber from the environmentwithin the central transfer station 110. For example, if the processingchamber will generate plasma during processing, it may be helpful toclose the slit valve for that processing chamber to prevent stray plasmafrom damaging the robot in the transfer station.

In some embodiments, the processing chambers are not readily removablefrom the central transfer station 110. To allow maintenance to beperformed on any of the processing chambers, each of the processingchambers may further include a plurality of access doors 170 on sides ofthe processing chambers. The access doors 170 allow manual access to theprocessing chamber without removing the processing chamber from thecentral transfer station 110. In the embodiment shown, each side of eachof the processing chamber, except the side connected to the transferstation, have an access door 170. The inclusion of so many access doors170 can complicate the construction of the processing chambers employedbecause the hardware within the chambers would need to be configured tobe accessible through the doors.

The processing platform of some embodiments includes a water box 180connected to the transfer chamber 110. The water box 180 can beconfigured to provide a coolant to any or all of the processingchambers. Although referred to as a “water” box, those skilled in theart will understand that any coolant can be used.

In some embodiments, the size of the processing platform 100 allows forthe connection to house power through a single power connector 190. Thesingle power connector 190 attaches to the processing platform 100 toprovide power to each of the processing chambers and the centraltransfer station 110.

The processing platform 100 can be connected to a factory interface 102to allow wafers or cassettes of wafers to be loaded into the platform100. A robot 103 within the factory interface 102 can be moved thewafers or cassettes into and out of the buffer stations 151, 152. Thewafers or cassettes can be moved within the platform 100 by the robot117 in the central transfer station 110. In some embodiments, thefactory interface 102 is a transfer station of another cluster tool.

In some embodiments, the second pre-clean chamber 150 is a plasmaprocessing chamber. The plasma processing chamber of some embodimentsexposes the substrate to a decoupled plasma comprising helium.

Referring to FIG. 7, some embodiments use a plasma assembly 380 with aslot 382. The plasma forms in the plasma cavity 384 and flows throughthe slot 382 toward the substrate surface 300. The view shown in FIG. 7is a cross-sectional view in which the slot 382 extends out of the page.The slot 382 through which the plasma formed in plasma cavity 384 flowshas edges 386. In some embodiments, the plasma has a high ion energy andconcentration adjacent the edges 386 of the slot 382.

One or more embodiments of the disclosure are directed to methods offorming metal oxide films. A metal oxide film can be formed by anysuitable method known to the skilled artisan. Suitable methods include,but are not limited to, atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), epitaxial growth andoxidative growth. In some embodiments, the metal oxide film is depositedor formed by an atomic layer deposition process in which the substrateis sequentially exposed to a metal precursor and a reactant to form themetal oxide.

The metal oxide film can be any suitable metal oxide depending on theprocess being performed and the device being manufactured. In someembodiments, the metal oxide film is a low-k dielectric, materials withdielectric constants less than about 12 or high-k dielectrics. In someembodiments, the metal oxide comprises aluminum oxide. In someembodiments, the metal oxide consists essentially of aluminum oxide. Asused in this specification and the appended claims, the term “consistsessentially of aluminum oxide” means that the metal oxide film isgreater than or equal to about 95%, 98% or 99% aluminum and oxygenatoms. In some embodiments, the aluminum oxide film comprises less thanor equal to about 2.5%, 2.4%, 2.30%, 2.2%, 2.10%, 2.0%, 1.9%, 1.80%,1.70%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1% or 1.0% carbon, on an atomicbasis. In some embodiments, the aluminum oxide film comprises less thanor equal to about 0.5%, 0.4%, 0.3%, 0.2% or 0.1% nitrogen, on an atomicbasis.

In some embodiments, the metal oxide film comprises aluminum oxideformed by sequential exposure of the substrate to an aluminum precursorand an oxygen reactant. The aluminum precursor can be any suitablecompound that can form aluminum oxide. In some embodiments, the aluminumprecursor comprises trialkylaluminum or an aluminum halide. In someembodiments, the trialkylaluminum comprises trimethylaluminum (TMA). Insome embodiments, the aluminum precursor consists essentially of TMA. Asused in this manner, the term “consists essentially of TMA” means thatthe aluminum containing reactive component of the aluminum precursor isgreater than or equal to about 95%, 98% or 99% TMA on a weight basis,excluding the amount diluent, carrier or inert gases that might beincluded.

The oxygen reactant can be any suitable oxygen reactant that can reactwith the surface species generated or formed by exposure to the aluminumprecursor. In some embodiments, the oxygen reactant comprises one ormore of water, oxygen, ozone, peroxide, N₂O, NO₂ or NO. In someembodiments, the oxygen reactant comprises water vapor. In someembodiments, the oxygen reactant consists essentially of water vapor. Asused in this manner, the term “consists essentially of water vapor”means that the oxygen containing reactive species in the oxygen reactantis greater than or equal to about 95%, 98% or 99% water vapor, on amolar basis.

The sequential exposures to the metal precursor and the oxygen reactantcan be repeated until a metal oxide film has been formed to apredetermined thickness or to a predetermined number of cycles (eachcycle is one exposure to metal precursor and oxygen reactant). In someembodiments, the deposition method comprises a CVD reaction and themetal precursor and oxygen reactant are mixed in the gas phase and themetal oxide film is deposited to a predetermined thickness.

After formation to the predetermined thickness, the metal oxide film isexposed to a decoupled plasma to lower the wet etch rate and/or dry etchrate of metal oxide film. The decoupled plasma can be formed in a remoteplasma source (like that of FIG. 7) and allowed to flow into theprocessing region of the processing chamber to react with the metaloxide film on the substrate. In some embodiments, the decoupled plasmacomprises one or more of He, H₂ or O₂. In some embodiments, thedecoupled plasma comprises helium. In some embodiments, the decoupledplasma consists essentially of helium. As used in this manner, the term“consists essentially of helium” means that the plasma species isgreater than or equal to about 95%, 98% or 99% helium, on an atomicbasis.

In some embodiments, the decoupled plasma comprises helium and oxygen.In some embodiments, the decoupled plasma consists essentially of heliumand oxygen. As used in this manner, the term “consists essentially ofhelium and oxygen” means that the plasma species is greater than orequal to about 95%, 98% or 99% helium and oxygen, on an atomic basis.The ratio of the helium to oxygen in the decoupled plasma can be varied.In some embodiments, the He:O₂ ratio is in the range of about 1:10 toabout 10:1, or in the range of about 1:5 to about 5:1, or in the rangeof about 1:2 to about 2:1, or about 1:1.

In some embodiments, the decoupled plasma is a directional plasma. Asused in this specification and the appended claims, the term directionalplasma means a plasma exposure in which a bias is applied to thesubstrate or substrate support to drive ions and/or radicals in theplasma to move toward the substrate. A non-directional plasma may have asource power (Ws) applied to the plasma source only. A directionalplasma may have a source power (Ws) applied to the plasma source and abias power (Wb) applied to the substrate or substrate support. In someembodiments, the decoupled plasma is a non-directional plasma and thesource power is in the range of about 1000 W to about 5000 W, or about2000 W.

In some embodiments, the decoupled plasma is a directional plasma andthe source power is in the range of about 100 W to about 500 W, or therange of about 200 W to about 400 W, or about 250 W, and the bias poweris in the range of about 100 W to about 500 W, or in the range of about150 W to about 400 W, or about 200 W. In some embodiments, the methodcomprises a source power and no bias power. As used in this manner, theterm “no bias power” means that there is no intentional bias applied tothe substrate or substrate support. In some embodiments, the methodcomprises a source power and a bias power.

The metal oxide film thickness can be deposited to a predeterminedamount prior to exposure to the decoupled plasma. In some embodiments,the decoupled plasma is exposed to the metal oxide film more than onceduring deposition of the final thickness of the metal oxide film. Insome embodiments, the substrate is exposed to the decoupled plasma afterno more than 20, 30, 40, 50, 60, 70, 80, 90 or 100 atomic layerdeposition cycles to deposit the film.

In some embodiments, the wet etch rate of the metal oxide film afterexposure to the decoupled plasma is lower than prior to plasma exposure.In some embodiments, the plasma exposed metal oxide film has a wet etchrate in very dilute HF (1:1100 HF:H₂O) is less than or equal to about 50Å/min, 45 Å/min, 40 Å/min, 35 Å/min, 30 Å/min, 25 Å/min, 20 Å/min, 15Å/min or 10 Å/min. In some embodiments, the wet etch rate in very diluteHF is less than or equal to about 50%, 45%, 40%, 35%, 30%, 25%, 20% or15% of the wet etch rate of the film prior to exposure to the plasma.

In some embodiments, the plasma exposed metal oxide film has a wet etchrate in a mixture of 1:1:50 hydrogen peroxide:ammonium hydroxide:waterat 70° C. less than or equal to about 105 Å/min, 100 Å/min, 95 Å/min, 90Å/min, 85 Å/min, 80 Å/min, 75 Å/min, 70 Å/min, 65 Å/min, 60 Å/min, 55Å/min, 50 Å/min, 45 Å/min or 40 Å/min. In some embodiments, the wet etchrate in 1:1:50 hydrogen peroxide:ammonium hydroxide:water at 70° C. isless than or equal to about 50%, 45%, 40%, 35%, 30%, 25%, 20% or 15% ofthe wet etch rate of the film prior to exposure to the plasma.

EXAMPLES

Aluminum oxide films were deposited by atomic layer deposition usingtrimethylaluminum and water. The aluminum oxide films were thensubjected to decoupled plasmas. The change in thickness of the aluminumoxide films was determined and the results are collected in Table 1. Itwas observed that the decouple plasma treatment had little to no effecton the thickness of the film.

TABLE 1 Ws (W) Wb (W) Pressure (mT) Time (s) ΔThickness (Å) O₂/H₂ Plasma2000 — 20 180 0.2 2000 — 200 180 1.6 250 225 100 20 1.4 250 225 100 90−2.2 O₂/He Plasma 2000 — 20 180 −0.4 2000 — 7 180 −0.3 250 225 100 200.4 250 225 100 90 −6.0 He Plasma 2000 — 20 180 −0.7 2000 — 7 180 −2.1250 225 100 20 −0.3 250 225 100 90 −3.2

The effect of the plasma treatment on the film composition showed thatthe decoupled plasma treatment had little to no effect on the filmcomposition.

The effect of the plasma treatment on the wet etch rate using verydilute HF (1:1100 HF:H₂O) at room temperature was measured and theresults are shown in Table 2.

TABLE 2 Ws (W) Wb (W) Pressure (mT) Time (s) WER (Å/min) O₂/H₂ Plasma2000 — 20 180 90.5 2000 — 200 \0 111.7 250 225 100 20 120.6 250 225 10090 124.0 O₂/He Plasma 2000 — 20 180 23.8 2000 — 7 180 21.7 250 225 10020 116.8 250 225 100 90 120.6 He Plasma 2000 — 20 180 60.7 2000 — 7 18059.7 250 225 100 20 7.4 250 225 100 90 13.4 No Plasma — — — — 62.8 — — —— 62.3

The films were also etched using a 1:1:50 mixture of H₂O₂:NH₄OH:H₂O at70° C. and the results are shown in Table 3.

TABLE 3 Ws (W) Wb (W) Pressure (mT) Time (s) WER (Å/min) O₂/He Plasma2000 — 20 180 92.1 3000 — 20 90 97.2 2000 — 20 90 104.4 He Plasma 250200 100 60 72.9 250 400 100 60 36.6 250 225 20 60 50.3 250 225 100 180143.7 No Plasma — — — — 127-130

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or it can be moved from the first chamber to one ormore transfer chambers, and then moved to the separate processingchamber. Accordingly, the processing apparatus may comprise multiplechambers in communication with a transfer station. An apparatus of thissort may be referred to as a “cluster tool” or “clustered system,” andthe like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, degassing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentinvention are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific steps of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,degas, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants. According to one or moreembodiments, a purge gas is injected at the exit of the depositionchamber to prevent reactants from moving from the deposition chamber tothe transfer chamber and/or additional processing chamber. Thus, theflow of inert gas forms a curtain at the exit of the chamber.

The substrate can be processed in single substrate deposition chambers,where a single substrate is loaded, processed and unloaded beforeanother substrate is processed. The substrate can also be processed in acontinuous manner, similar to a conveyer system, in which multiplesubstrate are individually loaded into a first part of the chamber, movethrough the chamber and are unloaded from a second part of the chamber.The shape of the chamber and associated conveyer system can form astraight path or curved path. Additionally, the processing chamber maybe a carousel in which multiple substrates are moved about a centralaxis and are exposed to deposition, etch, annealing, cleaning, etc.processes throughout the carousel path.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support andflowing heated or cooled gases to the substrate surface. In someembodiments, the substrate support includes a heater/cooler which can becontrolled to change the substrate temperature conductively. In one ormore embodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe invention. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the invention.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

1. A method comprising: forming a metal oxide film on a substratesurface by ALD using water as an oxidant; and exposing the metal oxidefilm to a decoupled plasma comprising one or more of He, H₂ or O₂, tolower the wet etch rate of the metal oxide film.
 2. The method of claim1, further comprising repeatedly forming the film and exposing the filmto the decoupled plasma sequentially to deposit a film of apredetermined thickness.
 3. The method of claim 1, wherein the filmcomprises aluminum oxide.
 4. The method of claim 3, wherein forming thealuminum oxide film comprises sequentially exposing the substratesurface to an aluminum precursor and an oxygen reactant.
 5. The methodof claim 4, wherein the aluminum precursor comprises trimethylaluminumand the oxygen reactant comprises water.
 6. The method of claim 1,wherein the decoupled plasma is a directional plasma.
 7. The method ofclaim 6, wherein the directional plasma is a remote plasma formed in aplasma assembly having a slot with edges through which the plasma flows,the plasma having a high ion energy and concentration adjacent the edgesof the slot.
 8. The method of claim 1, wherein the decoupled plasmaconsists essentially of helium or a combination of helium and oxygen. 9.The method of claim 1, wherein the metal oxide film has a wet etch ratelower than 50 Å/min in 1100:1 water:HF at room temperature or in amixture of 1:1:50 peroxide:ammonium hydroxide:water at 70° C.
 10. Amethod comprising: forming an aluminum oxide film on a substrate surfaceby sequential exposure to an aluminum precursor and water; and exposingthe aluminum oxide film to a decoupled plasma comprising a mixture ofoxygen and helium, the decoupled plasma having a source power and nobias.
 11. The method of claim 10, wherein the aluminum precursorcomprises trimethylaluminum.
 12. The method of claim 11, wherein thealuminum oxide film has a wet etch rate lower than 30 Å/min in 1100:1water:HF at room temperature.
 13. A method comprising: forming analuminum oxide film on a substrate surface by sequential exposure to analuminum precursor and water; and exposing the aluminum oxide film to adecoupled plasma consisting essentially of helium, the decoupled plasmahaving a source power and a bias power.
 14. The method of claim 13,wherein the decoupled plasma is a remote plasma formed in a plasmaassembly having a slot with edges through which the plasma flows. 15.The method of claim 14, wherein the metal oxide film has a wet etch ratelower than 20 Å/min in 1100:1 water:HF at room temperature or less thanabout 75 Å/min in a mixture of 1:1:50 peroxide:ammonium hydroxide:waterat 70° C.
 16. The method of claim 7, wherein the plasma has a high ionenergy and concentration adjacent the edges of the slot.
 17. The methodof claim 1, wherein the decoupled plasma consists essentially of helium.18. The method of claim 10, wherein the decoupled plasma consistsessentially of helium and oxygen.
 19. The method of claim 14, whereinthe plasma has a high ion energy and concentration adjacent the edges ofthe slot.
 20. The method of claim 13, wherein the decoupled plasmaconsists essentially of helium.